The present invention relates to an injection assistance device for an injection device and to an injection set provided with the said injection assistance device, these devices allowing a product to be injected safely and at an accurate injection depth into an injection site.
In this application, the distal end of a component or of a device is to be understood as meaning the end furthest from the user's hand and the proximal end is to be understood as meaning the end closest to the user's hand. Likewise, in this application, the “distal direction” is to be understood as meaning the direction of injection, and the “proximal direction” is to be understood as meaning the opposite direction to the direction of injection.
In order to administer a medicinal product to a body, particularly the human body, there are various possible routes depending on the place in the body at which the said product is to be injected: thus, the product may be injected intravenously, intramuscularly, subcutaneously, into a joint, or else intradermally. In many of these latter cases, and, particularly when injecting subcutaneously, the depth to which the needle is inserted and therefore at which the product is injected is particularly significant. Thus, it is possible to observe an adverse immunological reaction if, for example, a product that should have been injected into the subcutaneous tissues is finally injected into the intradermal tissues.
The operation of injecting a product using a syringe is particularly delicate. The patient may make an unforeseen movement or alternatively the person administering the injection might make a wrong move. Thus, errors in the depth to which the needle is inserted are particularly difficult to avoid and discrepancies of just a few millimeters may, themselves alone, lead to errors in injection depth.
Likewise, once the needle has been inserted, it is important to guarantee that this insertion depth is maintained throughout the injecting of the product so as to guarantee the correct injection depth.
As far as subcutaneous injection is concerned, there are various injection techniques currently used. Some users prefer to pinch the skin before inserting the needles, others prefer not to, and still others angle the syringe before inserting it into the skin, it being possible for this angle to vary from one user to another. The result of all this is that the depth to which the needle is inserted and therefore at which the product is injected may itself also vary, with the unpleasant consequences mentioned above.
Furthermore, in this kind of operation, it is also important to avoid any needlestick injury due to the exposed needle, whether this be before or after injection.
In addition, to limit the apprehension felt by the patient, particularly in the case of injections administered by the patient himself, it is desirable for the injection device not to look like a conventional syringe and/or for the needle not to be visible or to be visible only a little prior to insertion.
Finally, injecting a product using traditional injection devices generally entails at least two manual steps. For example, in the case of syringes, one manual step is to hold the body of the syringe in order to insert the needle into the injection site, another step consists in pressing on the plunger rod in order to administer the injection, the progression from one step to the other generally entailing moving the fingers with respect to the syringe.
There therefore remains a need for an injection assistance device and for an injection set which are made safe, that is to say which make it possible to limit the impact of undesired movements of the patient and/or of the user in order to prevent a variation in the depth to which the needle is inserted when administering the injection so as to avoid unintentionally injecting the said product at an inadequate depth, limiting the number of manipulations to be carried out by the user, limiting the risk of needlestick injury both to the patient and to the person administering the injection, limiting the apprehension felt by the patient and making the giving of the injection easier.
Documents US 2005/033230 and US 2003/0014018 describe injection devices comprising a hollow body for receiving the product to be injected, and grasping means, said grasping means being attached to, or part of, said hollow body. Documents U.S. Pat. No. 5,176,643 and WO 03/074111 describe injection devices for which the insertion length of the needle may vary in the insertion position.
There also remains a need for such an injection assistance device and an injection set that allow the user to be certain of causing the needle to penetrate the injection site to a predetermined insertion depth and, in addition, guarantee that the injection is administered at this predetermined depth.
There also remains a need for such an injection assistance device and an injection set that allow the needle to be kept at a constant insertion length, at least during the injection step, regardless of any increase or release of distal pressure exerted by the user on the injection device.
Moreover, it is important that the user be able to adjust the dose to be injected before proceeding with any injection step and/or to perform a vein test to prevent injection in the vein.